Terminal for electric resistances



TERMINAL FOR ELECTRIC RESISTANCES Filed Sept. 17. 1927 Iwvemfor 'Ruam OPPE'NHEJM ATTOIQNEY Patented Jan. 19, 1932 UNITED STATES PATENT QFFICE RENE OPPENHEIM, or GENNEVILLIERS, FRANCE, ASSIGNOR T0 socm'rr. monm LE cannons, or emmnvramnns, FRANCE TERMINAL FOR ELECTRIC RISISTANCES Application filed September 17, 1927, Serial No. 220,210, and in [France July 22, 1927.

This invention relates to resistances used in electrical apparatus, and more particularly to the resistancesused as heating elements and the means for connecting such resist- 5 ances in the electric circuit.

Resistances of the type descnbed generally consist of refractory bodies having a low conductivity of current. Due to this low conductivity, the passage of the electric current 10 increases the temperature of the resistance to a great extent; the resistance may even be raised to a red heat. Resistances of this type are commonly made of oxy-carborundum and the like.

Due to the high temperatures which such resistances withstand, it is very difficult to'secure the resistances to connecting plugs so as to connect the resistance in the electric circuit, because of the fact that such connecting plugs must themselves be able to withstand high temperatures since they are in contact with the resistances, and still make perfect contact therewith.

An object of the invention is to provide an arrangement whereby the connecting plug is able at all times to make perfect contact with the resistance despite the temperature of the latter.

A further object is to provide an arrangement which avoids all the disadvantages of the devices of thetype described which have formerly been used.

I attain these objects and other objects which will appear from a consideration of the following description by providing an arrangement whereby the ends of the resistance are kept at a relatively low temperature, so that the connecting plugs secured thereto may also be kept at a relatively low temperature to permit of perfect contact with the ends of the resistance.

The invention will be clearly understood by referring to the accompanying drawing which shows in vertical section an embodiment of my invention.

In the drawing 0: refers to a resistance of the type described, shown in tubular form. inserted in each end of the tubular resistance a and extending a relatively great distance therein is a plug 5 composed of a material which is a good conductor'of heat and electricity such as, for example, carbon graphite. The plug is fastened to the resistance by means of a conductive cement 0.

Plug I) also extends outside the resistance a, and to this outside extending portion and to part of the resistance a. itself is secured an annular member at which is also composed of a good electricit and heat conducting material such as carbon graphite. Member (i is preferably fastened to the plug 6 and resistance a by means of a cement 6 similar to cement 0.

As plug 6 is a good conductor of heat, the end portion 7 of the resistance a is not raised to a high temperature, but instead is maintained at a relatively low temperature. Since annular member a? contacts mostly with the end portion 7'', member 0? also is maintained at a relatively low temperature. Thus there will be no tendency for member d to deteriorate or expand unduly, and a perfect contact between it and the lead of the conductor of electricity to which it is connected is ensured. Even though the inner end of each plug 7) may be raised to a high temperature, the remainder of the plug will not be heated to an undesirable extent, since it is practically completely covered by the relatively cool end portions f of the resistance.

it is often desirable to render the resistance airproof, and this may be accomplished by the application thereto of an enamel which is capable of withstanding the high temperatures to which the resistance is subject.

The formula of a suitable enamel is as follows:

53 parts of white sand.

12 parts of oxide of tin.

13 parts of oxide of lead.

21 parts of carbonate of potash.

This enamel is heated, cooled and ground in accordance with the. usual methods of manufacturing enamel and applied to the resistance and heated to a temperature of approximately 1000.

The cements 0 and e referred to above may be made, for example, from a silicon base mixed with an argillaceous agglomerant, and after being interposed between members 5 preferably heated also be provided with caps of carbon gra hite havin such dimensions that too great cating. 0 the ends of the resistances is prevented.

It will be evident that by means of the invention it is possible to dnsure at all times a perfect contact between the electricit conuotor leads and the resistance, and t is by means of a very economical arrangement.

As the invention may be realized in other ways than those set forth above, the scope of the invention is to be limited only by the following'claims.

I claim as my invention 1. Means for providing eii'ective electrical contact between electrical conductors and the end of a high temperature resistance, comprisingv the combination, with a resistance member havin low electrical and thermal conductance, 0% a pair of distinct co-operating conductmg members including an insorted plu of relatively high conductance disposed a jacent both the interior and end of said resistance member in effective electrical contact therewith, and an annular member havin relatively hi h conductance arranged ad acent the exterlorof said resistance member and the exterior of said plug in simultaneous efi'ective electrical contact with both said resistance member and said lug.

2. Means for providing a good e ect-rical contact between electrical conductors and the ends of a resistance having low electrical and thermal conductance comprising a central plug of high conductivity adjacent the interior and end of said resistance, an annular member of high conductivity adjacent the exterior of said resistance and the end of said central plug and a cement composed of a material of a silicon base with an argillaceous agglomerant for binding said plug and said annular member to the resistance.

3. Means for providing efi'ective electrical contact between electrical conductors and the end of a high temperature resistance, comprising the combination, with a resistance member having low electrical and thermal conductance, of a pair of distinct co-operating conducting members including an insorted plug of carbon graphite adj acent both the interior and end of said resistance member at one extremity thereof, and an annular member of carbon graphite arranged adjacent the exterior of saidoresistance member and the exterior of said gra hite plug in effective electrical contact w1th both said resistance member and said plug.

4. Means for providing a good electrical contact between electrical conductors and the ends of a tubular resistance having low electrical and thermal conductance comprisin a central plu of carbon raphite adjacent t 0 interior and having a s oulder ad acent the end of said tubular resistance and an annular member of carbon graphite adjacent the exterior of said resistance and the shoulders of said central plug.

5. Means forproviding a ood electrical contact between electrical con uctors and the ends of a tubular resistance having low electrical and thermal conductance com rising a central'plug of carbon graphite a jacent the interior and having a shoulder ad acent the end of said tubular resistance and an annular member of carbon graphite adjacent the exterior of said resistance and the shoulders of said central plug, said central plug being longer than said annular member.

6. Means for providing efiective electrical contact between the electrical conductors and the end of a high temperature resistance, comprisin the combination, with a resistance mem er havin low electrical and thermal conductance, o a pair of distinct co-operating conductin members including an inserted plu of re atively high conductance disposed a jacent the interior and the end of said resistance member in effective electrical contact therewith, an annular member having relatively high conductance arranged adj acent the exterior of said resistance member and the exterior of said plug in simultaneous effective electrical contact with both said resistance member and said plug, and a cement binding said plug and said annular member to said resistance member to form substantially a unit therewith.

7. Means forprovidin efiective electrical contact between electrica conductors and the end of a high temperature resistance, comprising the combination, with a resistance member having low' electrical and thermal conductance, of a pair of distinct co-operating conducting members includmg an inserted plug of relatively high conductance adj a cent the interior of said resistance member and extending beyond the extremity of the same, and an annular member havin relatively high conductance arranged a acent the exterior of said resistance member and also adjacent the exterior of 'said plug beyond the extremity of said resistance member in simultaneous contact with both said plug and said resistance member, so that the mutual contact of said plug and said annular member beyond the extremity of said resistance member is-eifective to seal in and cover the end thereof.

8. Means for providing efiective electrical conductance, of a pair of distinct co-operating conducting members including an inserted plug of relatively high conductance adj a cent the interior of said resistance member and extending beyond the extremity of the same, and an annular member having relatively high conductance arranged adjacent theexterior of said resistance member and also adjacent the exterior of said plug be- {10nd the extremity of said resistance memer in simultaneous contact with both said plug and said resistance member, so that the mutual contact of said plug and said annular member beyond the extremity of said resistance member is effective to seal in and cover the end thereof, one of said conducting members also making efiective contact with the covered end of said resistance member.

9. Means for providing efiective electrical contact between electrical conductors and the end of a high temperature resistance, comprising the combination, with a resistance member having low electrical and thermal conductance, of a pair of distinct co-operating conducting members including an inserted plug of relatively high conductance adjacent the interior of said resistance member and extending beyond the extremity of the same, and an annular member having relatively high conductance arranged adjacent the exterior of said resistancemember and also adjacent the exterior of said plug beyond the extremity of said resistance member in simultaneous contact with both said plug and said resistance member, so that the mutual contact of said plug and said annular member beyond the extremity of said resistance member is effective to seal in and cover the end thereof, and a cement binding said plug and said annular member to said resistance member to substantially form a unit therewith.

The foregoing specification of my connecting plug for electric resistances signed by me this 6th day of September, 1927.

RENE OPPENHEIM. 

